Communities across the country are grappling with different approaches to improving their schools. Introducing or expanding charter schools is one of the approaches that states and school districts have considered or implemented. Charter schools serve more than 5 percent of public school students nationwide and make up close to 7 percent of all U.S. public schools. Yet they can be deeply polarizing. This polarization can use up policymakers', educators' and community members' limited time, energy and resources, making it that much more difficult to find practical solutions to improve schools for all children. This guide is designed to counter this controversy by contributing to a more informed, civil dialogue about charter schools. It is the hope that the resources developed for this project enable policymakers, educators and communities to better grapple with decisions about whether and how to introduce or expand charter schools in their states or districts. Grappling with these decisions requires understanding a range of issues that researchers have addressed: What are charter schools' effects on student achievement? Who operates charter schools? How are they financed and governed? How do charter schools affect neighboring traditional public schools? This guide to research is a nonpartisan, nonideological overview of some of the key research on these and other aspects of charter schools. It provides policymakers, journalists and community members with an easily digestible summary of a very wide body of research, including studies that are typically accessible only to academics.